There are often problems in adapting a particular type of drive to the requirements of a system to be driven.
For example, in testing apparatus in which a member such as a printed circuit board must be cycled repeatedly between positions, the drive system must meet many special requirements. In many respects synchronous motors are an attractive drive option. However, the use of such a motor may require the use of sophisticated couplings to compensate for motor vibration; jerking during acceleration, overload, or stall conditions; or unequalized loading on multiple motors.